FIG. 1 shows a side view of a conventional transfer molding apparatus. There are provided lower and upper plates 1 and 2. The lower plate 1 is upwardly and downwardly movable. Reference numeral 4 denotes a post of the lower and upper plates 1 and 2. An upper and lower master dies 3 and 3' having a heating system 9 are disposed at the lower and upper plates 1 and 2, respectively.
A chase block 20, into which an epoxy molding compound is cured therein in order for a semiconductor package to be formed and has a plurality of cavities 22 with a semiconductor package-shaped body, is disposed in the upper and lower master dies 3. Reference numerals 11 and 12 denote a transfer ram and a hydraulic cylinder, respectively.
The chase block 20 is disposed at a lower master die 3'. An upper master die 3 has the same chase block symmetrically spaced apart from the chase block 20 disposed at the lower master die 3'. The upper and lower chase blocks 20 form a semiconductor package as one set.
As shown in FIGS. 2 and 3, first, second and third plates 25, 23, and 27 are laminated from the upper portion in order. A cavity 22 is formed on the upper surface of the first plate 25 in a half form of a semiconductor package body 30 to be formed. A runner 21 extended from the cavity 22 is formed, into which an epoxy molding compound flows.
The second plate 23 is referred to as an ejecting plate. It is disposed between the first plate 25 and the third plate 27 and is movable upwardly and downwardly. A plurality of ejecting pins 24 are threaded with the first and second plates 25 and 23. The upper portions of the ejecting pins 24 communicate with the cavity 22 of the first plate 25 and the runner 21. The ejecting pins 24 are protrudely extended beyond the upper surface of the cavity 22 and the runner 21 in cooperation with the up and down movements of the second plate 23, so that the molded semiconductor package can be ejected to the outside thereby.
First, the heater 9 is disposed into the upper and lower master dies 3 of the lower and upper plates 1 and 2 and is heated up to a proper molding temperature. When the molding work temperature is made, the lead frame is loaded on the lower chase block 20. The lower master die 3' ascends and then clamps with the upper master die 3.
Thereafter, the tablet of the epoxy molding compound (EMC) is introduced into the through hole formed within the upper and lower master dies 3 and 3'. The EMC having a predetermined pressure in a gel form is supplied into the cavity 22 in cooperation with the transfer ram 11. When the EMC filled in the cavity 22 of the chase block 20 is substantially cured, the ejecting pins 24 cause the molded semiconductor package 30 to escape to the outside in cooperation with the ejecting plate 23. The ejecting pins 24 are driven by the ejecting plate 23 upwardly and downwardly movable in cooperation with the hydraulic pressure.
However, since the conventional transfer molding apparatus is directed to molding the semiconductor package using one molding structure of the upper and lower master dies, the number of semiconductor packages is limited. In addition, after the molding is finished, the ejecting plates should be driven so as to eject the molded semiconductor package from the chase block, so it is inconvenient.
Meanwhile, FIG. 4 shows the multi-port type molding apparatus, and FIG. 5 shows the chase block of the molding apparatus. As shown therein, the chase block 20a has a plurality of cavities 22a (in the drawings, eight cavities are shown) which are linked by the runner 21. This method is directed to using a tiny tablet and a plurality of transfer rams 17, and the runner is short. In this method, since the upper and lower master dies form one molding structure and then mold the semiconductor package, the number of the semiconductor packages which are fabricated by one molding process is limited, so that mass production is very difficult.